Review of Recent Geological Literature. 119 
to this age the author refers the Cambrian limestone of China, (ex- 
clusive of that which carries Dorypyge). Dr. Frech considers that 
the Cambrian of the Argentine, of S. E. Australia and Tasmania, be- 
longs to the one Pacific development of the Upper Cambrian. 
One might take exception to some of the remarks in this essay 
as for instance that which makes the Durness limestone Lower Cam- 
brian; possibly the Torridon sandstone is intended; or that which 
makes Anomocare, Acrotreta and Acrothele as specially characteris- 
tic genera of the Rocky mountain Lower Cambrian. The Dorypyge 
of the Rocky mountain Cambrian is spoken of as having no spines to 
the pygidium, perhaps six spines was intended. 
Dr. Frech thinks that Mr. Walcott’s subdivisions of the American 
Cambrian into provinces is too minute, and suggests looking at the 
distribution of life in the Cambrian sea from a broader point of view; 
and in fact he makes his Cambrian sea basins in some cases cover the 
whole range of Cambrian time. To him this is a necessity where he 
undertakes to review the Cambrian geography of the globe, where he 
must in large regions depend on fragmentary and most imperfect 
data. The excellence of Walcott’s work is that he deals with a smaller 
area from which much more detailed information is available, and 
therefore he can give a clearer and more satisfactory view of geologi- 
cal changes, than if he had attempted a wider field. G..F. M. 
Maryland Geological Survey. Allegany County, 1900. pp. 323, PI. 
29. Eocene, 1901. Pp. 259. Pl. 64. Wa. Buttock Crark, Director. 
These two volumes are the first of two series to be issued by the 
Maryland survey. One series is to deal with county resources, bring- 
ing forward information of economic value. The other series is to 
deal with systematic geology and paleontology, embracing the entire 
sequence of Maryland formations, the information being of educa- 
tional and scientific interest. 
The report on Allegany county includes a chapter on the physio- 
graphy by Dr. Cleveland Abbe. It embraces a detailed discussion of. 
the surface features of the region, supplementing the author’s general 
report on the whole state in “Maryland Weather Service Report,” 
Vol. 1. Mr. Cleophas C. O’Harra gives a most excellent account of 
the geology of the county. His section on the interpretation of the 
sedimentary record gives an interesting and instructive account of 
the historical geology. Other chapters deal with mineral resources, 
soils, climate, hydrography, magnetic declination, forests, and flora 
and fauna. Allegany county is not a geological unit, since its 
structural and stratigraphic features extend far beyond the limits of 
the county. It is, however, well situated for the display of these 
features, which are thus of more than local interest. Structurally, it 
lies within the district of open folding; physiographically, it includes 
parts of the greater Appalachian valley and of the Allegany plateau; 
stratigraphically, it displays a continuous series of sediments from the 
Silurian to the Permian, rich in well preserved fossils. Its economic 
